In certain circumstances, the amount of humidity in an open or enclosed space can reach undesirably low levels. For example, the open atmosphere during the winter months is often described as having cold, dry air. The description of cold, dry air during winter months is based on a general principle of thermodynamics, warm air retains more moisture than cold air because the absolute humidity level of air is directly proportional to the temperature of the air. Accordingly, cold air during the winter months often has a lower absolute humidity level than warm air during the summer months.
In addition to cold, dry air found in open spaces, many enclosed spaces also experience undesirably low humidity levels, especially during the winter months when the air in the enclosed space is being heated. This is due in part to the low humidity ratios of outdoor air supplied to widely-used forced air heating systems, as well as electrically resistive heating systems found in many hotel, office, and commercial buildings.
Many times, the humidity of an open or enclosed space may have the overall desired level of humidity, but pockets of dry air, or zones, within the open or enclosed space may have undesirably low levels of humidity. These zones may be caused by temperature gradients from external sources, e.g., convection heater. or an individual may desire more humidity within a particular zone, such as a zone within the immediate area of the individual.
Significant problems are associated with low humidity, including aggravation of existing skin or respiratory problems, and an undesirably high static electricity buildup in clothing and other personal accessories.
Air humidifiers are well known in the art, and are used to control the humidity level of air in enclosed spaces, such as buildings, hotel rooms, homes, offices, and the like. Typically, these air humidifiers are permanent fixtures and are not designed for portable use.
While portable humidifiers are known, they typically require the user to supply the water source by filling a reservoir, hence eliminating any use of the humidifier when an external water source is absent, e.g., when driving an automobile. Some of these reservoirs are rigid and bulky, making them awkward to carry. In other portable humidifiers, the reservoir is flaccid, making the shape of the reservoir inconsistent and cumbersome to handle. A further problem associated with portable humidifiers having a refillable water reservoir is the risk of contamination of both the water and the reservoir by physical, biological or chemical pollutants.
Moreover, portable humidifiers commonly require a source of external power, e.g., from an electrical outlet or a battery pack. The requirement for having an external power supply increases the complexity of the portable humidifier, thereby increasing the cost and maintenance of the device.
Thus, a need exists for an apparatus and method which can be used to increase the humidity in a zone having undesirably low humidity levels which overcomes the foregoing and other disadvantages of presently available portable humidifiers.